Limits

Peter possessed an empathic ability that allowed him to duplicate or "absorb" the abilities of other evolved humans near him. As of Dying of the Light, his father Arthur has stolen this ability from him. Originally, Peter had to concentrate very hard to think about the person from whom he received his ability (Distractions). Eventually, he was able to use this ability almost as second nature, and occasionally without even knowing the person from whom he received the ability.

The exact range at which mimicry occurs is not known, but Peter could mimic Claude's ability from at least several meters away. He could duplicate Claude's ability almost immediately upon coming within range. Whether the maximum distance and minimum time is the same to mimic any ability is uncertain. Peter did not necessarily have to see other people's abilities in use to absorb them. In The Hard Part, Peter began to absorb Ted Sprague'sability even though Ted had not used it in his presence. Also he absorbed at least two abilities on Kirby Plaza during his fight with Sylar: Niki's enhanced strength and D.L.'s phasing. Niki was standing right next to him, but D.L. was much farther away. It has to be at this point that he absorbs D.L.'s ability, as Peter had never encountered D.L. before and never encountered D.L. again before his death. If this is so, he may also have absorbed Molly's clairvoyance and Micah's technopathy, but he has never displayed these abilities.

Peter's control over other abilities that he mimicked varied; Abilities that required active concentration seemed to be more difficult for him to manifest or control. Peter would typically absorb abilities involuntarily, but he might not be aware of absorbing an ability that requires active concentration to use.

Peter once stated that in order to recall another person's ability when they were not present, he had to remember how that person made him feel (Distractions). While amnesiac, Peter was still able to recall abilities, even without memories of the person from whom he learned them. He also has demonstrated the use of abilities absorbed from people that he wasn't aware had any, meaning that an absorbed ability is triggered when Peter feels an emotion linked to the person he absorbed the ability from, rather than remembering the actual person. For example, Peter is unaware of D.L.'s ability, who has been near him (Kirby Plaza). However, even having no recollection of D.L. because of amnesia, in Four Months Ago Peter used this ability in situations where he felt incarcerated or trapped (tied up in a chair and locked up in a cell at Primatech Research), something that D.L. has felt throughout his whole life.

Early on after getting his powers, Peter began having dreams of future events, an ability who's origin he was unaware of for quite some time despite accessing the power multiple times. Even his future self lacked knowledge of the source of this ability yet continued to put it to extensive use. It was later revealed that this power was his mother's and Peter was mimicking it without even being aware that his mother had a power at all. (The Second Coming)

"You know, before I hit the ground... when I knew what was about to happen, I had this flash... in my head, of this girl that I met in Texas. This cheerleader. She could heal herself. Oh, gosh, she's this sweet kid. Sad little smile, and she just... You were wrong! I don't have to cut her out! I have to remember her!"

Notes

In doing research for Peter's ability, Aron Coleitesaid that the Heroes crew consulted several scientists about the concept of mosaic DNA.

Press materials released before Heroes aired skirted the issue of Peter's abilities, saying instead that he was "trying to convince his brother he could fly." The exact nature of his ability did not become clear for several episodes.

Mohinder says that Peter's ability is "like a sponge" to the abilities of other evolved humans (and not like a "chameleon"), and it could be dangerous for him to get near someone with an "unstable" ability. (The Fix)

Claude opines that it is fitting for an "empath" to be a nurse, as though he has had a prior familiarity with people of Peter's ability or at least an ability that is similar to it. (The Fix)

In an interview, Tim Kring elaborated on the similarities and differences between Peter and Sylar's abilities, calling them "two halves of a similar coin".

"Both are able to absorb people's powers, but in two very different ways. Peter's is based on his empathy and his ability to connect with people and when he's around them. Sylar actually has to take your brain and do something with it."

When Peter yells at Isaac, some have speculated that he may have (unsuccessfully) used Eden's ability of persuasion. However this is more likely a reflection of production effects rather than the use of an ability. The sound effects for Eden's persuasive voice (listen) and Peter's yell (listen) are very different (Unexpected). In an interview, it is stated that the voice change was for the "coolness factor."

Despite Peter using multiple abilities simultaneously on several occasions, it was stated in an interview that Peter only has access to one ability at a time.

Despite being exposed to all of Sylar's abilities at Homecoming and then later on the couple he'd gained since then, Peter only ever demonstrated telekinesis and intuitive aptitude the latter of which required the help of a future Sylar to access.

In the original timeline Peter was exposed to enhanced memory due to Sylar stealing that from Charlie Andrews before Homecoming, but as Hiro changed history, Peter was never exposed to that power.

Trivia

Empathic mimicry is the first ability to be demonstrated on Heroes. When reading Charles Deveaux the stock pages, Peter fell asleep, and used this ability to access his mother's.